High-voltage rectifying system



Sept.j7, 1937. c. e. SMITH HIGH VOLTAGE RECTIFYING SYSTEM 2 Sheets-Sheet 1 Filed March 28, 1954 FIG.

m M mm R EL 0 vR T NA T Sept. 7, 1937. c. 6. SMITH- HIGH VOLTAGE RECTIFYING SYSTEM Filed March 28, 1954 2 Sheets-Sheet 2 FIG. 2

INVENTOR O-mRLEs 6 5mm (QM/W ATTORNEY Patented Sept. 7, 1937 UNITED STATES PATENT OFFICE HIGH-VOLTAGE RECTIFYING SYSTEM Application March 28, 1934, Serial No. 717,734

9 Claims.

This invention relates to a high-voltage rectifying system of the type utilizing space discharge tubes.

One of the objects of my invention is to devise a system using space discharge tubes which are capable of withstanding inverse voltages of high values.

A further object of my invention is to devise such a system in which the drop through the space discharge tubes in the conducting direction is substantially unaffected.

The foregoing and other objects of my invention will be best understood from the following exemplifications thereof, reference being had to the accompanying diagrammatic drawings,

wherein:

Fig. 1 represents schematically'a single-phase rectifying system embodying my invention; and

Fig. 2 represents schematically a full-wave rectifying system also embodying my invention.

In rectifying systems it is desirable that such systems be capable of rectifying very high voltages. Therefore, the individual rectifying units must be capable of withstanding these high voltages in the non-conducting direction so as to prevent the passage of any appreciable current during the inverse cycle. Difficulties have been encountered in systems of this kind, particularly those using gaseous discharge rectifiers in which flash-back or heavy surges of current in the reverse direction would occur when voltages greater than a certain value were applied across the gaseous discharge rectifiers. The voltage which such a system could rectify had to be considerably below that value. In accordance with my present invention, I have devised a system whereby gaseous discharge tubes may be used in such a rectifying system, and withstand much higher voltages than could ordinarily be applied to such devices.

In Fig. l I have shown such a gaseous discharge rectifier I having a thermionic cathode 2, and an anode 3, enclosed within a sealed envelope, such as a glass tube 4. The tube 4 contains some suitable gas or vapor, such as, for example, mercury vapor which may be furnished from a small quantity of mercury 5. The cathode 2 and anode 3 are spaced apart within the envelope 4, and are adapted to support an ionizing discharge between them through the mercury vapor. Surrounding the discharge path between the cathode 2 and the anode 3 is placed a tubular conducting member 6. The member 6 tends to create a substantially field-free space in the discharge path in which the discharge can readily be controlled by a magnetic field. The tubular conducting member 6 is connected to the anode 3 through a high resistance I. Some suitable means is also provided for creating a magnetic field transverse to the discharge path between the 5 cathode 2 and anode 3 across the space surrounded by the tubular member 6. This means may consist of a coil 8 wound on a magnetic core 9 and disposed external to the tube adjacent the portion surrounding the tubular mem- 10 her 6. The cathode 2, anode 3, and member 6 can take a wide variety of forms. For example, member 6 can be either solid or perforated, and only partly surround the discharge space adjacent to it. In some cases member 6 can be left 15 out altogether.

The particular gaseous discharge rectifier, illustrated by way of example in Fig. 1, is disclosed and claimed in the copending application of Percy L. Spencer, Serial No. 612,235, filed May 19, 20 1932. In said application a more complete description of this type of rectifier will be found.

I have found that the above rectifier will pref vent discharges in the reverse direction between the anode and the cathode even under the appli- 25 cation of very high voltages when a transverse magnetic field is set up in the space surrounded by the tubular member 6. I have also found that when the magnetic field in this space is substantially zero, the voltage drop in the conduct- 30 ing direction in the cathode 2 and anode 3 can be very low, and the presence of the tubular member 6 and its associated structure does not materially affect the drop through the tube in the conducting direction. In order to utilize this 35 tube for increasing the inverse voltage which can be applied to such a tube, I have devised a novel system, one embodiment of which is shown for example in Fig. 1. The tube may be connected in the usual ,rectifying system which may comprise 40 a transformer Ill having a primary winding ll connected to a source of alternating current, and a secondary winding l2 one end of which is connected to the cathode 2 and the other end of which is connected through a load or output 45 device l3 to the anode 3. The cathode 2 may be supplied with heating current through a portion M of the secondary winding l2. Any other suitable method of supplying heating current to the cathode 2 may likewise be utilized. The coil 8 50 may also be supplied with power from the secondary winding I2. In supplying power to said coil 8, I interpose between the coil 8 and the secondary winding l2 the following system. A phase-shifting device l5 which is adjustable and 55 5 phase-shifting device is connected to the primary l6 of a small auxiliary transformer H. The secondary l8 of this transformer is connected through an auxiliary rectifier I9 to the coil 8.

The operation of the device shown in Fig. 1 is substantially as follows. When the voltage applied across the rectifier I is in such a direction that the cathode 2 is negative and the anode 3 is positive, an intense ionizing discharge will pass between these two electrodes and current will flow through the output or load device I 3. During this part of the voltage cycle, the rectifier |8 which is connected in series with the'coil 8 will prevent current from flowing through the coil 8, and thus no magnetic field will exist in the space enclosed by the tubular member 8. Thus substantially no resistance to the passage of the discharge between the cathode and anode is exerted by the tubular member 6 and its associated structure during the conducting cycle of the space discharge device I. As soon as the voltage across the space discharge device I reverses in direction, the voltage across the secondary I! of the transformer l6 likewise reverses in direction and the rectifier l8 will pass current which will fiow through the coil 8. Thus a magnetic field will be set up transversely to the discharge path between the cathode 2 and the anode 3 within the space surrounded by the tubular member 8, and eifectively prevent the starting of any discharge between the cathode and anode. I have found that a comparatively small magnetic field during this portion of the cycle will permit the application of very high voltages be- 40 tween the anode 3 and the cathode 2 without any substantial discharge taking place through the space between these two electrodes. In order that the magnetic field set up by the coil 8 shall have been built up to the proper value during the 45 inverse voltage cycle applied to the space discharge device I, I have found that it is desirable to have some means for adjusting the time relationship between the magnetic field and the voltage applied to the space discharge tube. I have 50 found that a convenient way of adjusting this time relationship is to utilize a phase-shifting device, such as that illustrated at l5. By adjusting the voltage phase at the output terminals of this phase-shifting device, the time of building 5 up the magnetic field can be so controlled that the field is at the proper value to prevent the passage of a discharge before the inverse voltage across the space. discharge device has been built up to an excessive value.

the magnetic field likewise will decrease so that when the voltage again reverses and is impressed across the space discharge device in the conducting direction, the magnetic field set up by the 65 coil 8 will have disappeared, and thus offer no resistance to the starting of the discharge through the tube in the proper direction.

The arrangement shown in Fig. 1 can, of course, be adapted for use in rectifying systems 70 in which a plurality of phases are rectified. In

75 conduction in the inverse direction through the As the inverse volt 60 age across the space discharge device decreases,

rectifier. Of course other forms of plural phase rectifying systems could be used, and -I have shown another modification of such a system in Fig. 2.

Fig. 2 shows a full wave rectifying system utilizing two rectifiers and 2|, each having a cathode 22, an anode 23, and a tubular conducting member 24 enclosed within the usual sealed envelope 25. The envelopes 25 likewise may contain a suitable gas oryapor, such as, for example, mercury vapor. Each of the tubular members 24 may be connected through a high resistance 28 to its respective anode 23. In a manner similar to that shown in Fig. 1, each of the rectifiers 20 and 2| is provided with means for creating a transverse magnetic field across the discharge space between the cathode and anode, and this means may consist of a coil 21 wound upon a magnetic core 28. The coil 21 and its associated core 28 is disposed adjacent its associated rectifier so as to create a transverse magnetic field in the space surrounded by the tubular member 24. The two rectifiers shown in Fig. 2 may be connected in the usual full-wave rectifying system which may comprise a transformer 29 having a primary winding 30 connected to a source of alternating current and a secondary winding 3|. The secondary winding is provided with a center tap 32 from which a connection passes through an output or load device 33 to both of the cathodes 22. Each of the cathodes 22 may be supplied with heating current in any suitable manner, such as, for example,.by an auxiliary heating transformer 34. The outer ends of the secondary winding 3| are connected to the respective anodes 23 of the rectifying tubes 20 and 2|. connected one of the coils 21. However, the connections are transposed so that the coil 21 associated with the rectifying device 20 is connected in series with the anode of the rectifying device 2|, and likewise the coil 21 associated with the rectifying device 2| is connected in series with the anode of the rectifying device 20.

The operation of the device shown in Fig. 2 is substantially as follows. When the transformer 29 is energized, a voltage operates across the rectifying device 20 in such a direction so as to make the cathode negative and the anode positive, an intense ionizing discharge will pass between the cathode and anode, and current will fiow through the output device 33. At the same time this current will likewise pass through the coil 21 associated with the rectifying device 2|. During this time, in the rectifying device 2|, the cathode is positive and the anode is negative. Since it is desirable to prevent current from passing through the rectifying device 2|, during this part of the cycle it is desirable that a transverse magnetic field be set up within the tubular member 24 in order to prevent breakdown under the high inverse voltages which I contemplate using with such a system. As has been pointed out above, this is the condition which actually exists. When the voltage across the transformer 30 reverses, the current through the rectifying device 20 will cease, and likewise the magnetic field set up by the coil 21 associated with the rectifying device 2| will disappear, and thus the rectifying device 2| will be in condition to permit the passage of an intense discharge between its cathode and anode in the proper direction. When the rectifying device 2| starts to conduct current, it likewise will cause current to flow in. the coil 2! associated with the In series with each of the anodes is r ative to prevent a rectifying device 20, and prevent discharges in the inverse direction in said rectifying device 20 under the application of high inverse voltages. By properly designing the size of the coil 21 and its associated core 28, the magnetic field set up by these elements will be sufficient to enable the rectifying devices 2|] and 2| to withstand extremely high inverse voltages without conducting current in the inverse direction.

Although I have shown rectifiers of the type in which rectification is dependent upon the temperature of the anode being comparatively low so that it does not emit electrons, my invention may also be used in devices in which the anode is not necessarily of this type. The anode, for example, can be made of a metal which under operation is raised to a sufiiciently high temperature to emit electrons. Under these, conditions the transverse magnetic field will effectively prevent conduction in the reverse direction, and comparatively high voltages may be impressed across the tube in the inverse direction without having substantial conduction of current through the tube in the reverse direction. In some instances it may be desirable to actually heat the electrode corresponding to the anodes shown in the figures. Under these conditions, by varying the phase of the transverse magnet field with respect to the voltage impressed across the tube, the tube may be made to reverse its direction of rectification, thus passing direct current in one or the other direction through the output circuit in accordance with the relationship of the transverse magnetic field to the applied tube voltage.

The invention is not limited to the particular details described above as many equivalents will suggest themselves to those skilled in the art. For example, the rectifying tubes which are used may be of any convenient type. The rectifying tubes in a plural phase rectifying system may be combined into a single tube in which each of the anodes has associated with it the proper means to resist conduction in the inverse direction. Also the means for preventing conduction in the inverse direction may take a wide variety of forms as will be apparent to those skilled in the art. It is accordingly desired that the appended claims be given a broad interpretation commensurate with the scope of the invention within the art.

What is claimed is:

1. A high-voltage rectifying system comprising a space discharge rectifier having a cathode and an anode adapted to support an ionizing discharge between them, control means interposed between said anode and cathode for preventing a discharge from passing between said cathode and anode, a source of alternating potential connected between said cathode and anode, and means for energizing said control means to prevent a discharge from passing throughout substantially the entire time when said anode is negative with respect to said cathode and for deenergizing said control means to render it inoperdischarge from passing throughout substantially the entire time when said anode is positive with respect to said cathode.

2. A high-voltage rectifying system comprising a space discharge rectifier having a cathode and an anode adapted to support an ionizing discharge between them, auxiliary means for setting up a magnetic field in the discharge space between said cathode and anode for preventing a discharge from passing between said cathode and anode, and means for energizing said auxiliary means when said anode is negative with respect to said cathode and for deenergizing said means when said cathode is negative with respect to said anode.

3. A high-voltage rectifying system comprising a space discharge rectifier having a cathode and an anode adapted to support an ionizing discharge between them, and a conducting member disposed adjacent to said discharge space, auxiliary means for setting up a magnetic field in the discharge space adjacent said conducting member for preventing a discharge from passing between said cathode and anode, and means for energizing said auxiliary means when said anode is negative with respect to said cathode and for deenergizing said means when said cathode is negative with respect to said anode.

4. A high-voltage rectifying system comprising a space discharge rectifier having a cathode and an anode adapted to support an ionizing discharge between them, control means interposed between said anode and cathode for preventing a discharge from passing between said cathode and anode, means for energizing said control means to prevent a discharge from passing when said anode is negative with respect to, said cathode and for deenergizing said control means to permit a discharge to pass when said anode is positive with respect to said cathode, means for energizing said control means when said anode is negative with respect to said cathode and for deenergizing said means when said cathode is negative with 'respect to said anode, and means for adjusting the time relationship between said alternating potential and the energization and deenergization of said control means.

5. A high-voltage rectifying system comprising a space discharge rectifier having a cathode and an anode adapted to support an ionizing discharge between them, means for creating a substantially field-free space in the discharge space between said cathode and anode, auxiliary means for setting up a magnetic field in said field-free space between said cathode and anode for preventing a discharge from passing between said. cathode and anode, and means for energizing said auxiliary means when said anode is negative with respect to said cathode and for deenergizing said means when said cathode is negative with respect to said anode.

6. A high-voltage rectifying system comprising a space discharge rectifier having a cathode and an anode adapted to support an ionizing discharge between them, auxiliary means for setting up a magnetic field in the discharge space between said cathode and anode for preventing a discharge from passing between said cathode and anode, said auxiliary means comprising a coil, means for energizing said coil, including a source of alternating current and a rectifier connected in inverse phase relation with respect to said space discharge rectifier.

'7. A high-voltage rectifying system comprising a space discharge rectifier having a cathode and an anode adapted to support an ionizing discharge between them, auxiliary means for setting up a magnetic field in the discharge space between said cathode and anode for preventing a discharge from passing between said cathode and anode, said auxiliary means comprising a coil, means for energizing said coil, including a source of alternating current and a rectifier connected in inverse phase relation with respect to said space discharge rectifier, and an adjustable phaseshifting device for shifting the phase of the alternating potential applied to said rectifier.

Cal

tween said cathode and anode, a source of alternating potential connected between each cathode and anode, the control means for each rectifier unit being energized from the output of the other rectifier unit. 9. A high-voltage rectifying system comprising two space discharge rectifier units, each having a. cathode and an anode adapted to support an ionizing discharge between them, a source of alternating potential connected between each cathode and anode, auxiliary means for setting up a magnetic field in the discharge space between each cathode and anode for preventing a discharge from passing between said cathode and anode, said auxiliary means each comprising a coil, the coil for each rectifier unit being energized from the output of the other rectifier unit. CHARLES G. SMITH. 

